2024年大学英语四级模拟试题附答案.doc

最新大学英语四级模拟试题（一）Part Writing (30 minutes)Directions: For this part, you are allowed 30 minutes to write a short essay entitled The Popularity of Getting Certificates on Campus. You should write at least 150 words following the outline given below.1.大学校园内各种证书的报考十分炽热2.大学生考证的利弊3.考证面前，我的选择The Popularity of Getting Certificates on CampusPart Reading Comprehension (Skimming and Scanning) (15 minutes)Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1.For questions 1-7, choose the best answer from the four choices marked A), B), C) and D). For questions 8-10, complete the sentences with the information given in the passage.Main Energies for the BodyA balanced diet is one that provides an adequate intake of energy and nutrients for maintenance of the body and therefore good health. A diet can easily be adequate for normal bodily functioning, yet may not be a balanced diet.CarbohydratesCarbohydrates are a rapid source of energy, they are the bodys fuel. The bulk of a balanced diet should be made from carbohydrates. If eaten in an excess of the dietary requirements carbohydrates are easily stored as fats in the cells, although carbohydrate is the first source of energy in the body. An average adult requires about 12,000kJ of energy a day, most of this is supplied by the respiration of carbohydrates in the cells.Carbohydrates are used principally as a respiratory substrates, i.e. to be oxidized to release energy for active transport, macromolecule synthesis, cell division and muscle contraction. Carbohydrates are digested in the duodenum and ileum and absorbed as glucose into cells. Sources of carbohydrates such as starch are rice, potatoes, wheat and other cereals. Sugars are also carbohydrates, sources of sugars are refined sugar - sucrose, which is a food sweetener and preservative and fruit sugars - fructose. If the diet lacks carbohydrate stores of fat are mobilized and used as an energy source.ProteinsProtein is not a direct source of energy in the body, it is used primarily for growth and repair of body tissues while remaining an energy source as a last resort. Proteins fulfill a wide variety of roles in the body. They are broken down in the stomach and intestines to amino acids which are then absorbed. The body can only form 8 amino acids to build proteins from, the diet must provide Essential Amino Acids (EAAs) which are synthesized into proteins which can be structural, i.e. collagen in bone, keratin in hair, myosin and actin in muscle; metabolic enzymes, hemoglobin, protective antibodies and communicative hormones.Sources of protein include meat, fish, eggs and pulses. The diet needs to provide 8 EAAs as the body is unable to synthesis proteins without these molecules. 2 other amino acids are synthesized from EAAs so if the diet lacks the original EAAs these other two will not be present either. Phenylalanine is converted to tyrosine and methionine is converted to cysteine. Cells draw upon a pool of amino acids for protein synthesis which either come from dietary protein digested and absorbed in the gut and the breakdown of body protein such as muscle. However, unlike fats and carbohydrates there is no store of amino acids for cells to draw on, any amino acid in excess of immediate bodily requirements is broken down into urea and excreted. It is therefore important to maintain the dietary intake of protein everyday. If the body lacks protein, muscle wasting occurs as muscle is broken down.If protein is lacked in a diet a person develops kwashiorkor which is caused when high levels of carbohydrates are eaten to overcome the lack of protein in the diet. One symptom of kwashiorkor is the abnormal collection of fluid around the abdomen due to the lack of protein in the blood. The body cannot retain water by osmosis and fluid accumulates in tissues causing them to become waterlogged.Vitamin CategoriesVitamins cannot be synthesized by the body so must be supplied by diet. Vitamins have no common structure or function but are essential in small amounts for the body to be able to utilize other dietary components efficiently.Vitamins fall into two categories, fat soluble vitamins such as vitamin A, D, E and K which are ingested with fatty foods and water soluble vitamins such as the B group vitamins and vitamin C. Vitamins are known as micronutrients because only small quantities are required for a healthy diet, in fact fat soluble vitamins can be toxic in high concentrations, for example the body stores vitamin A, or retinol, in the liver as it is toxic if kept in high concentrations in the blood stream, a dose of more than 3300mg of vitamin A can be considered toxic. Water soluble vitamins such as vitamin C and B groups vitamins can be excreted in the urine if in excess in the diet.Vitamins AVitamin A is essential to the proper functioning of the retina in the eye and the epithelial tissues. A lack of vitamin A results in dry, rough skin, inflammation of the eyes, a drying or scarring of the cornea - xerophthalmia, which occurs when the secretion of lubricating tears is stopped, the eyelids become swollen and sticky with pus. Mucous surfaces of the eye may become eroded allowing infection to set in, leading to ulceration and destruction of the cornea. Night blindness - an inability to see in dim light can also occur. Rod cells in the retina of the eye detect light of low intensity, they convert vitamin A into a pigment, rhodopsin, which is bleached when light enters the eye. Rod cells resynthesis rhodopsin, but if there is a deficiency of the vitamin, rod cells can no longer function and the result is night blindness. Epithelial cells use retinol to make retinoic acid, an intracellular messenger used in cell differentiation and growth. Without retinoic acid epithelial cells are not maintained properly and the body becomes susceptible to infections, particularly measles and infections of the respiratory system and gut.Xenophthalmia is common among children whos diets consist of mainly cereals with little meat or fresh vegetables, this is common in Indonesia, Bangladesh, India and the Philippines.Vitamins DVitamin D, or calciferol, is another fat soluble steroid vitamin which functions to stimulate calcium uptake from the gut and its deposition in bone. vitamin D acts as a hormone when converted by enzymes in the gut and liver into an active form of active vitamin D, which stimulates epithelial cells in the intestine to absorb calcium. vitamin D is therefore essential in growing childrens diets to enable the growth of strong bones. Without adequate amounts of vitamin D children can develop rickets, which is the deformation of the legs caused when they lack calcium to strengthen the bones. In adults a lack of vitamin D in the diet can lead to osteomalacia, a progressive softening of the bones which can make them highly susceptible to fracture.Vitamin D is made by the body when exposed to sunlight and is stored in the muscles, however, if the skin is rarely exposed to the sunlight or is dark little vitamin D is produced. Foods such as eggs and oily fish are all rich in vitamin D.Vitamins KVitamin K, phylloquinone, is found in dark green leafy vegetables such as spinach and kale. It is a fat soluble vitamin which is involved in the clotting process of blood. In the intestines bacteria synthesize a number of important clotting factors which need vitamin K. Without vitamin K cuts can fail to heal and internal bleeding can occur.Vitamins CVitamin C is a water soluble vitamin, known chemically as ascorbic acid. It is found in citrus fruits such as oranges and lemons, and also in potatoes and tomatoes. The main function of vitamin C is the formation of connective tissues such as collagen. It is also known to be an antioxidant which helps to remove toxins and aids the immune system. A lack of vitamin C leads to Scurvy, a condition experienced by sailors on long journeys when they did not have fruit in their diets. Scurvy causes painful, bleeding gums. As vitamin C is water soluble, it is not toxic in high doses as it can be excreted in the urine, very high doses can however cause diarrhea.Vitamins BB group vitamins have a wide range of roles acting as co-enzymes in metabolic pathways. They are found in most plant and animal tissues involved in metabolism, therefore foods such as liver, yeast and dairy products are all rich in B group vitamins. Deficiency of B group vitamins include dermatitis, fatigue and malformation of red blood cells.1. An adult needs about 12,000kJ of energy a day from _.A. the cell B. the respiring process of carbohydratesC. fats in the cell D. a balanced diet2. Carbohydrates are ultimately absorbed into cells in the process of _.A. digestion B. respirationC. oxidization D. mobilization3. The Essential Amino Acids which build part of proteins can be obtained from_.A. stomach B. body tissuesC. the body D. the diet4. The ultimate cause of kwashiorkor is lack of _.A. protein B. carbohydratesC. vitamins D. diet5. Vitamins are called “micronutrients” in that _.A. excessive fat soluble vitamins can be excreted in the urine B. the body only requires small amount of vitaminsC. a dose of 3300mg of vitamins can be considered toxic D. the high concentrations of water soluble vitamins are toxic6. Night blindness is a disease normally caused by lack of _.A. fat soluble vitamins B. water soluble vitaminsC. vitamin A D. innate disability7. The main function of vitamin D is to prevent adults from _.A. the growth of strong bones B. fractureC. a progressive softening of the bones D. calcium uptake from the gut8. Although the human body produces vitamin D normally, it fails to do so if there is not enough _.9. The reason why vitamin C is seen as an antioxidant is that it drives _ out of the body.10. If you are in lack of B group vitamins, you should turn to _.Part III Listening Comprehension (35 minutes)Section ADirections: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A), B), C) and D), and decide which is the best answer. Then mark the corresponding letter on Answer Sheet 2 with a single line through the centre.11. A) He thinks hes very organized.B) He doesnt want to join the display.C) He doesnt think he should lead the study group.D) He knows someone who can lead the study group.12. A) He doesnt know where his brother keeps his computer.B) The woman should buy a used computer.C) He doesnt know how much computers cost.D) His brother paid too much for the computer.13. A) Its been to warm to wear the jacket.B) The jacket is too big for him.C) He doesnt like cold weather.D) He didnt buy the jacket until cooler weather arrived.14. A) He started the semester in a bad mood.B) Hes not usually bad-tempered.C) He has few responsibilities.D) He doesnt like the man.15. A) He forgot to cancel the reservation.B) They can go to the restaurant after the woman has finished working.C) He has to work late tonight.D) They dont have a reservation at the restaurant.16. A) Use bleach on his socks.B) Buy new white socks.C) Wash his red T-shirt again.D) Throw away his pink socks.17. A) He isnt satisfied with his progress.B) He wants to move up more quickly than hes presently doing.C) He has advance quickly enough in his career.D) He feels frustrated as he tries to move up the ladder.18. A) Try on a smaller sweater.B) Look for another style at a different store.C) Give the sweater away as a gift.D) Exchange the sweater for a bigger one.Questions 19 to 22 are based on the conversation you have just heard.19. A) Shes unable to attend the study session.B) She has seen a doctor recently.C) Shes concerned about medical care.D) She mentions the need for some medical tests.20. A) To improve the study skills of university students.B) To suggest changes in the student government.C) To give people the opportunity to speak with a politician.D) To discuss graduation requirements for political science majors.21. A) Graduate school application procedures.B) Funding for university education.C) Winning the confidence of voters.D) Preparing for an important test.22. A) Tell her what to study for the history test.B) Write a favorable letter of recommendation.C) Advise her about how to run an election campaign.D) Suggest a topic for a research paper.Questions 23 to 25 are based on the conversation you have just heard.23. A) Boston schools.B) Frontier life.C) Teaching requirements.D) Immigration patterns.24. A) She was a famous author.B) Her family later became famous landowners.C) She exemplifies the immigrant spirit.D) She invented some labor-saving farm equipment.25. A) To the library.B) To the movies.C) To a bookstore.D) To a travel bureau.Section BDirections: In this section, you will hear 3 short passages. At the end of each passage, you will hear some question. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A),B),C),and D). Then mark the corresponding letter on the Answer Sheet with a single line through the center.Passage OneQuestions 26 to 29 are based on the passage you have just heard.26. A) They were drawing pictures. B) They were watching TV.C) They were making a telephone call. D) They were tidying up the drawing room.27. A) They locked the couple up in the drawing room.B) They seriously injured the owners of the house.C) They smashed the TV set and the telephone.D) They took away sixteen valuable paintings.28. A) He accused them of the theft.B) He raised the rents.C) He refused to prolong their land lease.D) He forced them to abandon their traditions.29. A) They wanted to protect the farmers interests.B) They wanted to extend the reservation area for birds.C) They wanted to steal his valuable paintings.D) They wanted to drive him away from the island.Passage TwoQuestions 30 to 32 are based on the passage you have just heard.30. A) Through food. B) Through air.C) Through insects. D) Through body fluids.31. A) They ran a high fever. B)